According to current estimates, 61,800,000 people in America have one or more forms of cardiovascular disease. These diseases claimed 958,775 lives in 1999 (40.1 percent of all deaths). Atherosclerosis is a leading form of cardiovascular disease, which involves the slow build-up of fatty plaques on the arterial wall. This build-up can damage the vascular endothelium causing inflammation, a narrowing of the arteries and potential arterial blockages that can result in heart attacks. Atherosclerosis is a complex disease that starts in childhood and often progresses when people grow older. In some people it progresses rapidly, even in their third decade. Elevated levels of cholesterol, in particular LDL (low-density lipoprotein), and triglycerides in the blood have been associated with the development of fatty plaques, which can lead to generalized vascular damage, atherosclerosis and eventually heart attack. Atherosclerosis and cardiac disease is also associated with increased cardiovascular inflammation, specifically as measured by levels of circulating C-reactive protein (CRP).
One key strategy for reducing the risk of atherosclerosis has been to lower the levels of cholesterol in the blood. Cholesterol levels in many people can be controlled by diet, but for many patients diet changes alone are insufficient to reduce high cholesterol. In recent years, cholesterol lowering drugs such as Zocor® (simvastatin) and Lipitor® (atorvastatin) have been increasingly prescribed to help patients lower their cholesterol levels. These drugs however, are not equally effective in all patients and frequently are associated with significant adverse side effects. A second key emerging strategy is the reduction of CRP, an important indicator of vascular inflammation and independently associated with increased risk of cardiovascular disease. Thus, safer and more effective treatments for lowering cholesterol and for reducing the vascular inflammation associated with atherosclerosis are of great potential value.
Lactoferrin is a single chain metal binding glycoprotein. Many cell types, such as monocytes, macrophages, lymphocytes, and brush-border cells in the intestine, are known to have lactoferrin receptors. Lactoferrin is found mainly in external secretions of mucosal epithelia such as breast milk, saliva, tears, bile, and pancreatic fluid and has a wide array of functions related to host primary defense mechanisms. For example, lactoferrin has been reported to activate natural killer (NK) cells, induce colony stimulating activity, activate polymorphonuclear neutrophils (PMN), regulate granulopoeisis, enhance antibody-dependent cell cytotoxicity, stimulate lymphokine-activated killer (LAK) cell activity, and potentiate macrophage toxicity.
Recombinant human lactoferrin has previously been described as being purified after expression in a variety of prokaryotic and eukaryotic organisms including aspergillus (U.S. Pat. No. 6,080,559), cattle (U.S. Pat. No. 5,919,913), rice, corn, Sacharomcyes (U.S. Pat. No. 6,228,614) and Pichia pastoris (U.S. Pat. Nos. 6,455,687, 6,277,817, 6,066,469). Also described are expression systems for the expression of full-length human lactoferrins (e.g., U.S. Pat. No. 6,100,054). In all cases, part of the teaching is expression of the full length cDNA and purification of the intact protein whose N-terminal, after processing of the leader peptide, is the amino acid glycine. Nuijens et al. (U.S. Pat. No. 6,333,311) separately describe variants of human lactoferrin but their focus is limited to deletion or substitution of arginine residues found in the N-terminal domain of lactoferrin.
The present invention is the first to use a lactoferrin composition as a means of reducing cholesterol and cardiovascular inflammation and for treating or reducing atherosclerosis and cardiovascular disease.